/*
 * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
 * Copyright (C) 2013 Intel Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef WTF_PassOwnPtr_h
#define WTF_PassOwnPtr_h

#include "wtf/OwnPtrCommon.h"

namespace WTF {

template <typename T> class OwnPtr;
template <typename T> class PassOwnPtr;
template <typename T> PassOwnPtr<T> adoptPtr(T*);
template <typename T> PassOwnPtr<T[]> adoptArrayPtr(T*);

template <typename T> class PassOwnPtr {
public:
    typedef typename std::remove_extent<T>::type ValueType;
    typedef ValueType* PtrType;

    PassOwnPtr() : m_ptr(nullptr) {}
    PassOwnPtr(std::nullptr_t) : m_ptr(nullptr) {}

    // It somewhat breaks the type system to allow transfer of ownership out of
    // a const PassOwnPtr. However, it makes it much easier to work with
    // PassOwnPtr temporaries, and we don't have a need to use real const
    // PassOwnPtrs anyway.
    PassOwnPtr(const PassOwnPtr& o) : m_ptr(o.leakPtr()) {}
    template <typename U> PassOwnPtr(const PassOwnPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));

    ~PassOwnPtr() { OwnedPtrDeleter<T>::deletePtr(m_ptr); }

    PtrType get() const { return m_ptr; }

    PtrType leakPtr() const WARN_UNUSED_RETURN;

    ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
    PtrType operator->() const { ASSERT(m_ptr); return m_ptr; }

    bool operator!() const { return !m_ptr; }

    // This conversion operator allows implicit conversion to bool but not to
    // other integer types.
    typedef PtrType PassOwnPtr::*UnspecifiedBoolType;
    operator UnspecifiedBoolType() const { return m_ptr ? &PassOwnPtr::m_ptr : 0; }

    template <typename U> friend PassOwnPtr<U> adoptPtr(U*);
    template <typename U> friend PassOwnPtr<U[]> adoptArrayPtr(U*);
    template <typename U> friend class OwnPtr;

private:
    explicit PassOwnPtr(PtrType ptr) : m_ptr(ptr) {}

    PassOwnPtr& operator=(const PassOwnPtr&)
    {
        static_assert(!sizeof(T*), "PassOwnPtr should never be assigned to");
        return *this;
    }

    // We should never have two OwnPtrs for the same underlying object
    // (otherwise we'll get double-destruction), so these equality operators
    // should never be needed.
    template <typename U> bool operator==(const PassOwnPtr<U>&) const
    {
        static_assert(!sizeof(U*), "OwnPtrs should never be equal");
        return false;
    }
    template <typename U> bool operator!=(const PassOwnPtr<U>&) const
    {
        static_assert(!sizeof(U*), "OwnPtrs should never be equal");
        return false;
    }
    template <typename U> bool operator==(const OwnPtr<U>&) const
    {
        static_assert(!sizeof(U*), "OwnPtrs should never be equal");
        return false;
    }
    template <typename U> bool operator!=(const OwnPtr<U>&) const
    {
        static_assert(!sizeof(U*), "OwnPtrs should never be equal");
        return false;
    }

    mutable PtrType m_ptr;
};

template <typename T>
template <typename U> inline PassOwnPtr<T>::PassOwnPtr(const PassOwnPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
    : m_ptr(o.leakPtr())
{
    static_assert(!std::is_array<T>::value, "pointers to array must never be converted");
}

template <typename T> inline typename PassOwnPtr<T>::PtrType PassOwnPtr<T>::leakPtr() const
{
    PtrType ptr = m_ptr;
    m_ptr = nullptr;
    return ptr;
}

template <typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, U* b)
{
    return a.get() == b;
}

template <typename T, typename U> inline bool operator==(T* a, const PassOwnPtr<U>& b)
{
    return a == b.get();
}

template <typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, U* b)
{
    return a.get() != b;
}

template <typename T, typename U> inline bool operator!=(T* a, const PassOwnPtr<U>& b)
{
    return a != b.get();
}

template <typename T> inline PassOwnPtr<T> adoptPtr(T* ptr)
{
    return PassOwnPtr<T>(ptr);
}

template <typename T> inline PassOwnPtr<T[]> adoptArrayPtr(T* ptr)
{
    return PassOwnPtr<T[]>(ptr);
}

template <typename T, typename U> inline PassOwnPtr<T> static_pointer_cast(const PassOwnPtr<U>& p)
{
    static_assert(!std::is_array<T>::value, "pointers to array must never be converted");
    return adoptPtr(static_cast<T*>(p.leakPtr()));
}

template <typename T> inline T* getPtr(const PassOwnPtr<T>& p)
{
    return p.get();
}

} // namespace WTF

using WTF::PassOwnPtr;
using WTF::adoptPtr;
using WTF::adoptArrayPtr;
using WTF::static_pointer_cast;

#endif // WTF_PassOwnPtr_h
